Most commercially available automotive engines use fixed lift and duration valve timing events. As a result, there is a compromise between the best fuel economy, emission control, and engine power conditions.
Potentially better fuel economy, emission control, and other engine output benefits can be realized if the timing of these events can be varied depending on the engine operating mode.
This invention is directed to several embodiments of a phaseshifting mechanism changing the engine timing from a conventional schedule to accomplish the above objectives. The mechanism comprises a driving member and a member driven thereby hydraulically through a fluid to effect relative rotation between the two at times to change the phasing, a unique valve construction with helical grooving fluid connecting the valve with the driven member controlling the hydraulic operation.